The book of Genesis says God created the heavens and Earth in less than a week. Now, Catholic clergy are being asked to follow suit and keep their sermons to under eight minutes in a recommendation issued from the Vatican.

Archbishop Nikola Eterovic, the secretary general of the Synod of Bishops, says homilies should be brief to cater for people with short attention spans. Clergy should also work from an outline, rather than a script, to allow for better eye contact.

In a book called The Word of God, Eterovic proffers suggestions on how priests and deacons can improve the quality of sermons and retain churchgoers' interest.

"The homily in general should not go over eight minutes – the average amount of time for a listener to concentrate," he said, adding that clergy should keep abreast of current affairs so that a sermon addresses issues of local or national concern.

The archbishop also wrote that it was normal for churchmen to have patchy communication skills or to struggle with preparing homilies. To counter this, he suggests following the pope's lead by spending a week writing a sermon that is engaging and relevant.

His advice was welcomed by Father Andrew Headon, vice-rector of the Venerable English College in Rome, which trains men for the priesthood.

"There is a saying among clergy," he said. "If you haven't struck oil in seven minutes, stop boring."

Headon, who gives sermon-writing classes, said the recommendations were likely to be of use in the UK, where the church was competing against different media for people's attention.

"The hardest sermons to write are the shortest. You have to be really disciplined and they have to be extremely well-crafted. A sermon should not be a lecture, nor is it academic. You need to give spiritual food for thought that will stay with someone for a week."

One enterprising priest in Ireland has developed a different way to draw in parishioners pushed for time – abandoning the sermon altogether.

Father Michael Kenny introduced an experimental 15-minute mass in February because his 9am mass was only attracting three or four people. He pushed back the start time to 7.30am, promising his congregation they would be out the door by 7.45am.

Attendances at the small north Galway parish church have since increased to between 30 and 40 a service.

He told the Irish Independent a 9am start was "totally unsuitable" for people going to work or taking their children to school.